In pharmaceutical and food fields, examples of a method of producing a solid preparation, particularly a tablet, include a dry direct tableting method comprising the steps of mixing a drug and an additive and tableting the resulting mixture as it is, and a wet granulation tableting method comprising the steps of granulating a mixture of a drug and an additive in the presence of a binder solution or a proper solvent such as water, drying the resulting granules, and tableting the dried granules. When the drug or the additive has poor fluidity or formability in the dry direct tableting method, for example, a dry granulation tableting method comprising the steps of subjecting the mixture to roll compression (dry granulation), crushing and then tableting may be employed. In the wet granulation tableting method, an agitating granulator or a fluidized bed granulator may be used.
The dry direct tableting method has been employed frequently in recent years because it can be used even when a drug is sensitive to water or because its simple process facilitates process control. However, compared with the wet granulation tableting method, the dry direct tableting method usually requires a larger amount of the additive in order to secure formability. Examples of the additive having high formability include crystalline cellulose having high formability (JP 06-316535A), hydroxyalkyl cellulose fine particles (WO 2011/065350A), and low-substituted hydroxypropyl cellulose having high formability and high fluidity (JP 2010-254756A).
On the other hand, there is a recent tendency of reducing the size of tablet to make it easier to swallow and therefore decreasing an amount of additive such as a binder. Accordingly, a binder capable of enhancing the hardness of the tablet when added even in a small amount is demanded.